The present invention relates to apparatus for automatic prevention of unintended double exposure in annotatable archival microfiche recording systems employing an intermediate film to carry a record image from an imaging station to a transfer station where the microfiche film card receives the record image. The invention also relates to use of said apparatus to warn of failure to transfer the image.
There has been developed by the applicants and co-workers an archival hard copy microfiche recording system which reflects light off of a document placed on a document-receiving platform and projects an image of it in greatly reduced form onto an initially transparent intermediate dry silver film strip carried by a film head unit. The film strip is dispensed from a cassette mounted on the film head, and is fed by film advancing means to an imaging region where a selected area of the film strip to be exposed can receive the projected light image. A pressure element presses the selected area of the film strip against a planar backing aperture defining a projection plane and an imaging area, and the film is then exposed to the light image. The film head is next moved along guides from the imaging station to a developing station, where a hot shoe pressing against the exposed area of the film causes development of the image to form an opaque image in the exposed areas thereof. The film head is then moved to an image transfer station, where the image on the dry silver film is to be replicated on a positive initially opaque microfiche film card of the photo-developing type (See U.S. Pat. No. 4,137,078 issued June 30, 1979 to Izu and Ovshinsky). The microfiche card is held indexed on a movable carriage so that a predesignated frame of the card receives the image on the intermediate film. A pressure element presses the film card and the intermediate film strip together between the output prism of a flash lamp housing and a backing plate. Image transfer is accomplished by energizing the flash lamp to direct light through the intermediate film, immediately rendering transparent the previously opaque areas struck by the high intensity flash lamp light on the selected frame of the microfiche film card. To replicate a new image the film head is returned to the imaging station, where the cycle is repeated.
The microfiche card may be examined via a "read" mode of the system. With the film head positioned away from the imaging lens, the microfiche film card carriage, which is accurately locatable in x and y directions by means of an indexing system, is moved on a track to a station under the lens. An illumination system is moved next to the microfiche film card carriage and then the chosen frame of the card is projected back to the document receiving area.
The system also possesses the capability of "annotating" or "updating" existing records stored on the microfiche film. This arises from the nature of the two film systems used. The intermediate film is of the reversal type; dark areas on the chosen hard copy replicate as transparent areas and light areas replicate as opaque upon development. Hard copy having black lettering on a white page will thus replicate on the intermediate film as an opaque rectangle with transparent letters. The microfiche film, however, is an initially opaque photodeveloping positive film which is rendered irreversibly transparent where struck by high intensity light during flash exposure. Thus, dark markings on the original document replicate as irreversibly transparent images on an otherwise still opaque microfiche film frame. These remaining opaque regions on the microfiche film remain "annotatable", i.e. convertible in that they can be rendered transparent by a subsequent flash exposure. It is this aspect of the microfiche film that allows for updating of microfiche records. As used throughout this disclosure and in the appended claims the term "annotatable" will be understood to refer to a film that is capable of accepting a second image after exposure and development of a first image in the same general region.
Thus, if a copy of a document is imaged on a microfiche film card frame where the indicia on the document are dark lines on a light background, these dark lines are now stored as irreversible clear lines on the microfiche film card. To update the microfiche film card with new entries in a specified still convertible area of a microfiche film card frame one prepares on intermediate film a fresh image consisting of the new entries only. This is accomplished by using as a source for the new image a dark-line record on a white background placed on the document receiving platform, e.g. typewritten black text on white paper. The new image, consisting after development solely of transparent new entries on an otherwise opaque imaging area, is then replicated at the transfer station onto the microfiche film card frame. These new entries are thus replicated as additional irreversible clear indicia on the selected frame. Proper registry of the new record is achieved by using the "read" mode of the system to assist in orienting the new entries on the document receiving platform before the intermediate film is exposed to receive the new image. Here an image of the chosen frame to be updated is projected back onto the document receiving platform, using the "read" mode previously described. A white sheet of paper bearing the new record indicia is then placed on the document receiving platform and moved around until the new indicia are properly positioned with respect to the projected image of the microfiche film card. The frame is now updated by carrying out a conventional "record" cycle, i.e. the microfiche film card is returned to the transfer station, the film head is moved to the imaging station, whereupon the image of the new record indicia is projected, exposed, developed, and replicated onto the microfiche film card frame at the transfer station.
Such annotatable systems are inherently vulnerable to record wipeout by an unintended second exposure; accidental selection by the operator of an exposed microfiche film card frame in the belief that it is a fresh one can result in the superposition of a new record image over an old one, with concomitant obliteration of the old record. It is an object of this invention to provide a sensing means to distinguish between fresh frames and exposed ones, and to provide automatic prevention of accidental multiple exposure thereby.
It is equally basic to archival systems that a failure of the system to produce a record image on the microfiche film card be immediately communicated to the operator. In practice this is generally a result of failure of the flash lamp to fire. It is another object of this invention to provide sensing means to detect automatically such a flash failure.